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DDN Security Bulletin 06         DCA DDN Defense Communications System
1 Nov 89                Published by: DDN Security Coordination Center
                                     (SCC@NIC.DDN.MIL)  (800) 235-3155

                        DEFENSE  DATA  NETWORK
                          SECURITY  BULLETIN

The DDN  SECURITY BULLETIN  is distributed  by the  DDN SCC  (Security
Coordination Center) under  DCA contract as  a means of  communicating
information on network and host security exposures, fixes, &  concerns
to security & management personnel at DDN facilities.  Back issues may
be  obtained  via  FTP  (or  Kermit)  from  NIC.DDN.MIL  [26.0.0.73 or
10.0.0.51] using login="anonymous" and password="guest".  The bulletin
pathname is SCC:DDN-SECURITY-nn (where "nn" is the bulletin number).

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                       SUN RCP VULNERABILITY
 
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!                                                                       !
!   The following important advisory was issued by the Computer         !
!   Emergency Response Team (CERT) and is being relayed via the Defense !
!   Communications Agency's Security Coordination Center distribution   !
!   system as a means of providing DDN subscribers with useful          !
!   security information.                                               !
!                                                                       !
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			    CERT Advisory

			   October 26, 1989

			Sun RCP vulnerability

A problem has been discovered in the SunOS 4.0.x rcp.  If exploited,
this problem can allow users of other trusted machines to execute
root-privilege commands on a Sun via rcp.

This affects only SunOS 4.0.x systems; 3.5 systems are not affected.

A Sun running 4.0.x rcp can be exploited by any other trusted host
listed in /etc/hosts.equiv or /.rhosts.  Note that the other machine
exploiting this hole does not have to be running Unix; this
vulnerability can be exploited by a PC running PC/NFS, for example.

This bug will be fixed by Sun in version 4.1 (Sun Bug number 1017314),
but for now the following workaround is suggested by Sun:

Change the 'nobody' /etc/passwd file entry from

nobody:*:-2:-2::/:

to

nobody:*:32767:32767:Mismatched NFS ID's:/nonexistant:/nosuchshell


If you need further information about this problem, please contact
CERT by electronic mail or phone.


J. Paul Holbrook
Computer Emergency Response Team (CERT)
Carnegie Mellon University
Software Engineering Institute

Internet: <cert@SEI.CMU.EDU>
(412) 268-7090 (24 hour hotline)